Photochemical Kinetics of Vibrationally Excited Ozone Produced in the 248 nm Photolysis of O₂/O₃ Mixtures

Abstract

Infrared emission from vibrationally excited ozone was monitored as a function of time following pulsed laser photolysis of O3/O2 mixtures with total pressures from 300 to 1800 Torr at 295 K. The emission data obtained at 9.6 μm were analyzed by nonlinear least squares and by constructing χ2 surfaces. The results are entirely consistent with a conventional mechanism that includes the following reactions: (1a) O3 + hν → O(1D) + O2(aΔ); (1b) O3 + hν → O(3P) + O2; (2a) O(1D) + O2 → O(3P) + O2(1Σg +); (2b) O(1D) + O2 → O(3P) + O2; (3) O(3P) + O2 + O2 → O3(v) + O2; (4) O3(v) + O2 → O3 + O2; (5a) O2(1Σg +) + O3 → O + O2 + O2; (5b) O2(1Σg +) + O3 → O3(v) + O2; (6) O2(1Σg +) + O2 → O2 + O2. There is no evidence for participation by ozone excited electronic states, but the reaction time scales are not well separated, leading to complexities in the analysis. The measured rate constants k 3 (±σ) = (6.0 ± 1.1) × 10-34 cm6 s-1 and k 5 (±σ) = (2.26 ± 0.15) × 10-11 cm3 s-1 are in good agreement with literature values. The phenomenological rate constant k 4 (±σ) = (1.2 ± 0.2) × 10-11 cm3 s-1 is consistent with a model for vibrational deactivation. The measured value for the ratio k 1a k 2a/(k 1 k 2) = 0.86 ± 0.13 is combined with a literature value for k 1a/k 1 to give an improved estimate for k 2a/k 2 = 0.95 (+0.05/−0.13).

O2(a1Δ) quenching in the O/O2/O3 system

“…Detailed descriptions of the reaction kinetics of O/O 3 / O 2 /Ar gaseous mixtures can be found, for example, in Refs. [12,15,22,23].…”

“…where the singlet oxygen yield is 90% [14,15]. The O 2 (a 1 D) removal rate was monitored by observing the time evolution of the O 2 emission at a wavelength of k = 1268 nm.…”

Electronically excited molecular nitrogen and molecular oxygen in the high-latitude upper atmosphere

“…According to Green et al (2000) we believe the yield of the process (10) in inelastic quenching of metastable atomic oxygen by an oxygen molecule is equal to 0.95. Branching ratios for the production of v =0 and 1 are measured by Kalogerakis et al (2005).…”

Model of daytime emissions of electronically-vibrationally excited products of O<sub>3</sub> and O<sub>2</sub> photolysis: application to ozone retrieval

“…O 2 +hν(SRC)→O( 3 P)+O( 1 D) 2.60×10 −6 1.0 Rodrigo et al (1986), DeMore et al (1997) O 2 +hν(Lyman-α)→O( 3 P)+O( 1 D) 3.40×10 −9 0.48-0.58 Rodrigo et al (1986), Reddmann and Uhl (2003) O 3 +hν→O 2 (X, v=0-35 Streit et al (1976), Lee and Slanger (1978), Green et al (2000) O ( …”

“…In Table 2, the Einstein coefficient for emission of O( 1 D) at 630 nm and the rate constants of O( 1 D) deexcitation at collisional processes, as well as the quantum yields of electronically-vibrationally excited products of these processes, are presented. In Green et al (2000) the total quantum yield of…”